Integrated x-ray and charged particle active pixel CMOS sensor arrays using an epitaxial silicon-sensitive region

Stuart Kleinfelder; Hans Bichsel; Fred Bieser; Howard S. Matis; Gulshan Rai; Fabrice Retiere; Howard Wieman; Eugene Yamamoto

doi:10.1117/12.450826

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10 January 2003 Integrated x-ray and charged particle active pixel CMOS sensor arrays using an epitaxial silicon-sensitive region

Stuart Kleinfelder, Hans Bichsel, Fred Bieser, Howard S. Matis, Gulshan Rai, Fabrice Retiere, Howard Wieman, Eugene Yamamoto

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Proceedings Volume 4784, X-Ray and Gamma-Ray Detectors and Applications IV; (2003) https://doi.org/10.1117/12.450826
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

Integrated CMOS Active Pixel Sensor (APS) arrays have been fabricated and tested using X-ray and electron sources. The 128 by 128 pixel arrays, designed in a standard 0.25 micron process, use a ~10 micron epitaxial silicon layer as a deep detection region. The epitaxial layer has a much greater thickness than the surface features used by standard CMOS APS, leading to stronger signals and potentially better signal-to-noise ratio (SNR). On the other hand, minority carriers confined within the epitaxial region may diffuse to neighboring pixels, blur images and reduce peak signal intensity. But for low-rate, sparse-event images, centroid analysis of this diffusion may be used to increase position resolution. Careful trade-offs involving pixel size and sense-node area verses capacitance must be made to optimize overall performance. The prototype sensor arrays, therefore, include a range of different pixel designs, including different APS circuits and a range of different epitaxial layer contact structures. The fabricated arrays were tested with 1.5 GeV electrons and Fe-55 X-ray sources, yielding a measured noise of 13 electrons RMS and an SNR for single Fe-55 X-rays of greater than 38.

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Stuart Kleinfelder, Hans Bichsel, Fred Bieser, Howard S. Matis, Gulshan Rai, Fabrice Retiere, Howard Wieman, and Eugene Yamamoto "Integrated x-ray and charged particle active pixel CMOS sensor arrays using an epitaxial silicon-sensitive region", Proc. SPIE 4784, X-Ray and Gamma-Ray Detectors and Applications IV, (10 January 2003); https://doi.org/10.1117/12.450826

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